The present invention relates to a device for transporting agitatable material using a vibrator in general and more particularly to such a device used for the purpose of galvanically deposition aluminum from aprotic, oxygen-free and anhydrous aluminum organic electrolytic solution. More specifically, the present invention is related to an improvement in such a device having a vibrator conveyor trough mounted in a spiral around a center tube and surrounded by a tank. This tank contains a liquid into which the vibrator is partially submerged along with the center tube.
It is known that by surface finishing metallic components, their life span can be extended and new fields of application can be developed. For example, coatings of light metal and ferrous material are effective in protecting relatively non-precious metals whose surfaces can corrode under the effects of the atmosphere. By means of appropriate pretreatment, the components receive a polished surface free of unwanted surface film. The metallic coating can be supplemented by a secondary treatment.
During galvanic treatment, the agitatable small parts must be held together so that the individual parts make electrical contact with each other. On the other hand, the agitatable material to be treated should be sufficiently spread out so that metal deposition can take place over as great an article surface area as possible. This also provides an optimally uniform current density on all parts. A further important prerequisite for achieving perfect metal platings with a uniform layer of uniform thickness is the sufficient agitation of the material during the galvanic treatment. The devices for electrolytic surface plating (electroplating) are equipped with conveyors for transporting the agitatable material through an electrolytic solution. A continuous or periodic admission and removal of the material is made possible through the use of corresponding admission and exit sluices. In addition, both the motion of the material, and the mixing as well as transport of the material through the electrolyte should be done so that the material is treated gently and sensitive parts are not mechanically damaged during galvanic treatment. These requirements are not only relevant in the case of electrolytic surface plating (electroplating), in particular in mass electrolytic surface plating, but are also of significance for the electrochemical surface treatment of agitatable material in liquids, e.g. as during chemical and electrolytic pickling in acids or alkaline liquids, as well as during electrolytic degreasing in alkaline baths, and electrolytic polishing. During electrolytic surface treatment, the agitatable material is wired as a cathode or as an anode. For example, the circuit arrangement is applied such that the agitatable material is an anode during electrolytic polishing, whereas the agitatable material is preferably wired as a cathode during the deposition of aluminum.
The prior art discloses a device suitable for the purpose of mass electroplating, in particular for the galvanic deposition of aluminum, in which a vibrator with horizontal and vertical vibrating components is used to transport the agitatable material through the treatment bath. By utilizing inertial force, this vibrator transports the agitatable material in an upward direction within a spiral conveyor trough around a supporting pedestal which is connected to the conveyor trough. The vibrator is placed with the supporting pedestal in a gas-tight vessel which contains an electrolytic solution into which the vibrator is partially submerged. For example, vibrators having a skew effect or tilted guides can serve as motive agents. In addition, gravity conveyors in the form of downspouts can be provided. Such vibrators simply require a relatively low motive force for operation and make the gentle conveyance of the agitatable material possible. One thus obtains an intensive movement of material and good electrolytic exchange as well as a uniform current intake over the entire active surface of the spread out material (U.S. Pat. No. 4,670,120, which corresponds to DE-OS No. 35 24 510).
Another prior art device for the surface treatment of agitatable material includes a spiral conveyor which is secured to a centrally mounted supporting pedestal. This conveyor is provided with several steps, whose step height is calculated so that the material turns while falling, thus providing enhanced mixing. A larger number of such steps at the same slope of the conveyor, however, leads to a corresponding enlargement of the apparatus (EPA No. 0 209 015).
Despite these prior devices, there is a need for simplifying and improving device for transporting agitatable material in a liquid using a vibrator. In particular, there is a need to obtain better intermixing of the agitatable material in the conveyor trough.